The foregoing telescopic shaft is used, for example, as a steering shaft for a vehicle.
In addition, the telescopic shaft is used as an intermediate shaft for connecting a steering shaft and a steering mechanism such as a rack and pinion mechanism in a motor vehicle. In this case, the telescoping function of the telescopic shaft is utilized for adjusting the length of the intermediate shaft for absorbing relative displacement between a steering gear and a steering column during a drive of the vehicle. Or, the foregoing telescoping function is utilized for adjusting the length of the intermediate shaft for mounting the intermediate shaft in the vehicle.
There has been proposed a telescopic shaft of this kind, in which a plurality of rollable balls are interposed between corresponding axial grooves of an inner shaft and a tubular outer shaft and the both shafts are fit to each other (See, for example, Patent Document 1).
Patent Document 1: Japanese Unexamined Patent Publication No. 2001-50293